1. Field of the Invention
The present invention relates to moving-body detecting image sensors for generating an output based on the movement direction and speed of a moving body, and more particularly, to a moving-body detecting image sensor capable of generating an output based on the movement direction of a moving body, by processing an input signal sent from a plurality of light receiving elements.
2. Description of the Related Art
Charge coupled devices (CCDs) have been well known as elements used for picking up images. In many image processing systems, an image picked up by a video camera having a CCD is input, for example, to a personal computer (PC), and various processes are applied to the image data and the image is reproduced by software and hardware in the PC.
Using software for image processing increases the flexibility of the processing. When there are a large number of pixels, or an advanced process is executed, however, data transfer between the camera and the computer or between a memory and a processor in the computer limits the entire processing speed in many cases. Research has been actively made concerning high-speed algorithm and signal processing with a parallel architecture to eliminate the limitation.
In the research, however, a sequential processing method in which processing is sequentially applied to pixels which form an image is mainly used. Therefore, it is difficult to expect a dramatic higher speed and a dramatic higher function. On the other hand, so-called “vision chips” have been widely researched in which some information processing functions are taken into image sensors by the use of the progress of integrated-circuit technologies. The vision chips are described, for example, in “Modeling Selective Attention Using a Neuromorphic Analog VLSI Device,” written by G. Indiveri, Neural Computation, Vol. 12, No. 12, pp. 2857–2880, 2000, or in “High Performance Biomorphic Image Processing Under Tight Space and Power Constraints,” written by R. Etienne-Cummings et al., Autonomous Robots, Vol. 11, No. 3, pp. 227–232, 2001.
In the vision-chip research, however, relatively simple processes, such as noise removal and edge detection, have been mainly handled, and outputs are images obtained after the processes, in many cases. In applications to robot vision, for example, the “meaning” of an image is finally required, and software processing by the use of a computer needs to be applied to extract the meaning.